Hey guys. I don't remember why, but I thought it would be a good idea to wire my case using 18 awg solid wire. As I'm sure you can imagine, it's a pain in the a** to work with because its not the most flexible. So I'm looking to get some smaller wires so my build can FINALLY be completed.

Here is the layout :

There will be enough length between wires to hide them thoroughly and run them throughout the case.

I'm rather tired of dealing with such thick wires, so what awg wires should I be using for this?

you can use size 14 no issues, even old speaker wire, or cables from dead DC power supplies, just cut the ends off, stuff like that, no issues at all. I used just 14 and been running 12v led strips for over 2 years on the same wires, no issues, no heat, leds do not take up much current, you wont have any issues.

Depends on the amp rating of the LEDs. You might find 14AWG a little bit too thick though! When you say you're using solid AWG18 do you mean it's a single core rather than stranded wire. If so 18AWG stranded is a lot easier to work with.